1. Write a recursive function to compute the number of words of length n, where the letters come from the English alphabet (which has 26 letters. Ignore capitalization.)
2. Write a recursive function to compute the number of words of length n, where every "Q" is followed by a "U".
3. Compute the number of ways to sum to n that don't include the numbers 2 or 4 in the sum. 
4. Compute the number of ways to sum to n using only even numbers.